This invention relates to the production of glass-insulated microwire with amorphous or microcrystalline microstructure.
A method for casting microwires in glass insulation is disclosed in U.S. Pat. No. 3,256,584 in which the charge metal and glass are melted by means of a high field inductor, after which a metal-filled capillary is drawn and collected onto a receiving bobbin. However, the issue of controlling the microstructure of the final wire has not been addressed.
Amorphous metals have no grain boundaries, can be readily doped, have a zero-temperature dependence of resistivity and possess good electrical and magnetic properties. Amorphous and microcrystalline microwires provide substantial improvements of certain properties compared to wires of similar compositions having equilibrium crystalline structures. Microcrystalline metals often have intermediate properties of amorphous and crystalline metals. The electrical resistance of the amorphous wires increases from 160 K.OMEGA./m up to 2500 K.OMEGA./m, and it becomes possible to obtain both positive and negative thermal coefficient of resistance. In the case of magnetically soft amorphous microwires, the initial magnetic permeability increase 5-7 times, and can reach 20.times.103. The mechanical strength of these amorphous microwires increases.
Microcrystalline and amorphous microwires are well suited for applications such as sensors of temperature, static and dynamic pressure, velocity and liquid or gas consumption.
It is the object of the present invention to prepare amorphous or microcrystalline glass-insulated microwires.